1. Field of the Invention
The present invention relates to a sensor for detecting the oxygen content in the intake tract of an internal combustion engine. The invention is also directed to an internal combustion engine having an oxygen sensor of this type.
2. Related Art
In internal combustion engines, it is, in many situations, desirable to detect the oxygen content in the intake air in the intake tract of the internal combustion engine. This is the case, for example, if the internal combustion engine is equipped with a facility for exhaust-gas recirculation into the intake tract. In this case, it is the intention to determine the exhaust-gas recirculation rate by detecting the oxygen content. Without exhaust-gas recirculation, the O2 content in the intake air is approximately 21%, and this decreases with increasing exhaust-gas recirculation fraction.
According to the prior art, use is made here, as oxygen sensors, of conventional linear lambda probes such as are used in the exhaust tract of the internal combustion engine. Since such Lambda probes become very hot in the exhaust gas, they have an expensive housing that can withstand high temperatures. Therefore, in the prior art, cumbersome and expensive devices are used for measuring the oxygen fraction in the intake air.